43 testimony to the model‘s canonical role: it is a skew with respect to the Black-Scholes-Merton flat-line relationship between strike price and implied volatility. If an area of economics is too diverse and is changing too fast, empirical enquiry into Barnesian performativity and counterperformativity becomes very difficult. If different theories or models are used by different participants, and if they are frequently discarded and replaced, then their use may have effects on their ―truth,‖ but identifying those effects will be problematic: it will be difficult to know where to start.24The circumstances that make the enquiry feasible in the case of option theory –a widely-used canonical model, and decades of empirical tests of the model –are probably not unique, but they may not be common. Although empirical investigations of Barnesian performativity and counterperformativity may therefore be difficult, one virtue of the notions is that in respect to an economic theory or model they prompt us to ask a question additional to the two natural questions (that is, is the theory or model analytically tractable, and does it adequately represent some economic process?) The additional question is this: what would be the effects of the widespread use of the theory or model? That third question was, for example, asked prior to 1987 of the use of option theory in portfolio insurance, but not often enough and influentially enough (see MacKenzie 2004). 24These difficulties would attend any investigation of whether post-1987 patterns of option pricing are Barnesian performative effects of models other than Black-Scholes-Merton.